1. Field of the Invention
The invention relates generally to the field of drilling and surveying wellbores through Earth formations. More specifically, the invention relates to methods for drilling and surveying a wellbore using coiled tubing.
2. Background Art
U.S. Patent Application Publication No. 2004/0118611 filed by Runia et al. describes methods and apparatus for drilling and surveying a wellbore in subsurface Earth formations in which a set of survey instruments is placed within a pipe or conduit used to convey a drill bit into the wellbore. The set of survey instruments is able to exit the interior of the pipe or conduit by a special tool causing a center segment of the drill bit to release, thus creating an opening for the survey instruments to leave the pipe or conduit and enter the wellbore below the bottom of the pipe or conduit.
The method and apparatus disclosed in the Runia et al. publication is intended to be used on so called “jointed” pipe, wherein a length of such pipe is made by threadedly assembling segments or “joints” of such pipe into a “string” extended into the wellbore. It is known in the art to carry out operations in a wellbore using so-called “coiled tubing.” In coiled tubing operations, a reel of tubing is transported to the wellbore site. Wellbore tools of various types, including drilling tools, are affixed to the end of the coiled tubing, and the coiled tubing is unwound from the reel so as to extend into the wellbore. Coiled tubing wellbore operations have advantages such as much faster time to exchange wellbore tools by retrieving the coiled tubing from the wellbore by spooling the coiled tubing back onto the reel. Such winding is considerably faster than uncoupling the threaded connections used with conventional threadedly coupled pipe. There is a need to have wellbore drilling and surveying techniques as disclosed in the Runia et al. publication that are usable with coiled tubing.